captcha to defeat form spammers - Page 2

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Re: captcha to defeat form spammers

David E. Ross wrote:
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They can even create problems for normally sighted people without
perceptual disabilities. Oftentimes I have been unable to tell whether a
particular stroke was part of a letter or part of the obfuscation.

Re: captcha to defeat form spammers

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Unfortunately for CAPTCHAs, image processing software is able to
defeat any capture that might be easy for a person to read... The
eventual consequence will be CAPTCHAs that no-one can read.

Of course, the reason they're a bad idea is encoded into their name. A
Turing test is where a human tries to distinguish between a human and
a computer. Since no computer program has passed the test, no computer
program is qualified to administer the test by definition... (and even
then it'd be the wrong test - automatic isn't necessarily spam, manual
isn't necessarily not spam)

Conversely, a very simply written spamfilter will catch >99.9% of
spam. It's nowhere near as complex a problem as email spam. The big
giveaway is unexpected URL markup in the content, but adding a few
other regex-based tests helps.


Re: captcha to defeat form spammers

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That is the obvious solution for 99.9% of cases and so far I have found
it effective. It is the big sites that have the real problem. For
instance Yahoo, that want to block the automated creation of thousands
of accounts which can then be used for nefarious purposes like spamming
Yahoo Groups. What besides CAPTCHA can these sites use?

Day by day I'm getting more depressed with the Internet which seems to
be sinking in a swamp of spam. All the methods being used against it are
just fire-fighting and not getting to the root of the problem.

Philip Baker
PJB Software
Thalasson Web Resources

Re: captcha to defeat form spammers

On Thu, 22 Feb 2007 17:36:34 -0800, "David E. Ross"

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Can anyone give me a URL for a reputable CAPTCHA which I can use on my
webpage? That would be helpful, rather than sparking some sort of
meaningless argument. Is there anything on SourceForge for example?

Re: captcha to defeat form spammers

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No, no one can give such a URL because CAPTCHA is fundamentally
flawed. It's not just that there are better or worse implementations,
it's that the whole idea is unworkable.

As Jukka said when you started this thread:
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I'll go one further and give you a specific URL: /

Read that, and stop sighing after flawed concepts. Just like
challenge-response, CAPTCHA is a misguided "solution" to a real

Stan Brown, Oak Road Systems, Tompkins County, New York, USA
HTML 4.01 spec: /
validator: /
CSS 2.1 spec: /
validator: /
Why We Won't Help You:

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